1. Field of the Invention
The present invention relates to an apparatus for filtering particles from a liquid and more particularly to an apparatus for trapping large foreign objects in a wash liquid in an automatic washer.
2. Description of the Prior Art
Automatic clothes washing machines are provided with a pump which among other things recirculates wash liquid within the wash tub. As the wash liquid is recirculated throughout the clothes load, foreign objects such as coins, buttons, bobby pins, toothpicks and other similar objects become entrained in the wash liquid and are carried toward the pump. It is necessary to intercept and trap these foreign objects prior to their reaching the pump so that they will not cause damage to the pump. Various attempts have been made to filter out these foreign objects which can range in size, shape and density from heavy disc shaped objects such as coins and buttons to floatable cylindrical rod shaped objects such as toothpicks. This wide range of sizes, shapes and densities presents a particular filtering problem in automatic washers which the present invention overcomes.
Various means have been employed between the washing vessel and pump to intercept foreign objects, among them being (a) gravity type traps which provide a low water velocity region for heavier than water objects to settle out and collect, (b) grid types, and (c) labyrinth types. All of the above types have various advantages and drawbacks. Type (a), in principle, will only intercept heavier than water objects, while objects of wood or light plastic such as toothpicks will pass. An advantage is that the objects trapped will not typically accumulate lint, partly because they are out of the main water stream and partly because they are free to shift position easily. This type also requires several inches of vertical space which may or may not be readily available. Type (b), can be made to intercept objects as small as desired and of any material, but will typically accumulate lint on both the grid and the objects intercepted. Eventually the accumulation of lint will restrict waterflow through the system unless removed. Removal of the lint is a nuisance and is dependent on the vigilance of the operator. Type (c), can be made to intercept objects of almost any size, shape and material. It can also be made to pass lint, at least when free of foreign objects. However, the accumulated foreign objects tend to take on the characteristics of a grid and collect lint themselves. This is especially true if the objects are held in a region of high water velocity and restricted freedom to move about and thereby, perhaps, release their lint.
U.S. Pat. No. 2,919,568 discloses a straining device which is adapted to prevent the passage of long narrow objects such as nails, matches, paper clips and bobby pins which comprises a plate having circular perforations therein which is positioned fairly close to the bottom wall of the tub and has the perforations spaced laterally from the drain opening such that long cyindrical shaped objects are unable to pass through the perforations to the drain opening.
U.S. Pat. No. 3,006,477 discloses a filter which utilizes a settling chamber and two annular outlet passageways to remove lint and heavy articles from the wash water.
U.S. Pat. No. 3,236,386 discloses a foreign articles trap wherein wash liquid is directed through an annular opening and through two 180 degree turns and which also employs an annular settling chamber.
U.S. Pat. No. 3,590,606 discloses a tube in the foreign objects trap arranged with the outlet spaced between the top and the bottom of the outer tube such that heavier than water objects settle to the bottom of the tube and lighter than water objects float to the top of the outer tube while the washing liquid passes out the outlet opening.
U.S. Pat. No. 1,254,025 discloses a filter screen for use in removing sand, gravel and other sediment from water lines in which a cylindrical or flat circular screen is used which has perforations therethrough with outwardly extending fingers or projections which are used to protect the perforations from clogging.
U.S. Pat. No. 2,533,422 discloses a house gutter screen which is used to prevent leaves and twigs from collecting in house gutters in which a plate is used to cover the gutters which has a plurality of domes embossed in the plate having side openings forming drain openings. The domes are used to hold flat solid objects such as leaves away from the drain openings so that water can drain easily into the gutters while the leaves and other debris are kept out of the gutters.